BACKGROUND: Patient and disease characteristics are often mentioned by clinicians as possible risk factors for psychological distress among women with breast cancer. However, either these factors have not been evaluated or when they were evaluated, results were inconclusive. METHODS: Potential risk factors for psychological distress were assessed among 205 patients with newly diagnosed breast cancer by home interview 3 and 18 months after surgery. RESULTS: At 3 months, proportions of women with high distress reporting 0-1, 2-3, 4-5, and 6-15 stressful life events in the 5 years preceding diagnosis were 17%, 20%, 28%, and 37%, respectively (P = 0.006). High levels of psychological distress were present in 63.1% of women with a history of depression, compared with 14.3% of those with no such history (P = 0.0001). Associations of these factors with distress also were present 18 months after diagnosis. At 18 months only, distress was more frequent in women with regional disease (44%) than in those with localized disease (22%) (P = 0.006). Age, education, and marital status had little or no association with levels of psychological distress. CONCLUSIONS: Number of stressful life events before diagnosis and history of depression appear to be strong indicators of the risk of psychological distress and may be useful for identifying patients with breast cancer in need or more intense psychosocial support.